P4 - Explaining Motion Flashcards
Instantaneous speed is…
The speed of an object at a particular instant
Displacement of an object at any given moment is…
its net distance from its starting point together with an indication of direction
Distance time graphs…
- Steeper gradient = higher speed
- distance on y axis
- time on x axis
- flat time means object is stationary
Speed time graphs…
- speed on y axis
- time on x axis
- straight diagonal line = constant acceleration
- flat line = steady speed
- curved line = increasing acceleration or deceleration
Acceleration is…
- The change in speed of an object in a given time interval
- Calculated by change in velocity/time taken
- Unit is m/s^2
Instantaneous velocity is…
An object’s instantaneous speed together with indication of direction
Velocity time graphs…
Same as speed time graphs but when the line goes below the x axis it changes direction
When two objects interact…
Both experience a force and these forces form an interaction pair
Two forces in an interaction pair are…
Equal in size and opposite in direction
Rockets work because…
- As the fuel burns, exhaust gases are produced
- The rocket engine pushes these forces out backwards
- The gases push the space shuttle forwards with the same size force in the opposite direction
The resultant force on an object is…
The sum of all the individual forces on an object, taking their directions into account
When a resultant force acts on an object…
It causes a change of momentum in the direction of force
Change in momentum of an object…
Is proportional to the size of the resultant rode acting on the object and to the time for which it acts
Driving forces for an object moving in a straight line…
- driving force> counter force means the object will speed up
- driving force=counter force means the vehicle will move at a constant speed
- driving force
In situations involving a change in momentum, the longer the duration of the impact, the __________ the average force for a given change in momentum
Smaller
If the resultant force on an object is 0…
The momentum does not change:
- If stationary it stays at rest
- If already moving it continues at a constant velocity
The energy of a moving object is ________ energy
Kinetic
As an object is raised its GPE ___________ and as it falls its GPE ___________
Increases, deceases
When a force moves on an object…
It does work
When work is done…
Every is transferred to an object. When the object does the work energy is transferred to something else
The ______ the mass of the object and the _______ the object is moving, the greater its kinetic energy
Greater, faster
Air resistance or friction cause the gain in an object’s kinetic energy to be ______ the the work done on it by applied force in the direction of motion, because some energy is dissipated through heating
Less
The law of conservation of energy…
Energy may be transformed from one form to another but it cannot be created or destroyed
Average speed is…
A measure of distance travelled in a given period of time: s=d/t
